This invention relates to a sound field control device and method for simulating a sound field of a small space such as a concert hall in a large space such as an open outdoor space and a large space inside of a building.
It is important in an acoustic design for a concert hall designed mainly for performance of classical music to pay much attention to the structure and the influence of reflected sounds in order to facilitate listening of each performer on the stage to his own performance and also other's performance and maintain acoustic characteristics concerning "reverberation", "loudness", "spatialimpression" etc.
Since it is difficult to obtain such reflected sounds in an outdoor space, it is necessary to synthesize necessary reflected sounds electrically and create a sound field having naturalness which will satisfy both performers and audience.
FIG. 2 shows a conventional sound field control device in an outdoor concert site. This outdoor concert site has a stage 14. The stage 14 is surrounded by a wall 10 in its top and bottom, both sides and back portion and is open in the direction of front audience seats 12. The audience seats 12 are not surrounded by a wall but are completely open.
Microphones 18 are set close to musical instruments 16 on the stage 14. Main loudspeakers 20 and 22 are provided on both sides of the stage 14 and auxiliary loudspeakers 24 and 26 are provided outside of the main loudspeakers 20 and 22. The main loudspeakers 20 and 22 function to add reverberation to sounds from the stage 14 and constitutes a so-called PA (public address) device. The auxiliary loudspeakers 24 and 26 supplement tone volume for the main loudspeakers 20 and 22.
Inside or in the vicinity of the audience seats 12 is provided an input adjusting table (mixing console) 28. Sounds collected by the microphones 18 are applied to the input adjusting table 28 where they are adjusted in level by operation of an operator (mixer). The sounds are then imparted with reverberation by echo machines 30 and 32 and thereafter are propagated from the main loudspeakers 20 and 22 and the auxiliary loudspeakers 24 and 26.
The conventional sound field control device shown in FIG. 2 has the following problems:
(1) Since the operator creates a sound field on the basis of his own acoustic impression, the sound field thus created often becomes different from a sound field which musicians and conductors desire to create.
(2) Since acoustic similarity between the audience seats 12 and the s rage 14 is insufficient, the sound field created by this device becomes different from a sound field in a general indoor concert hall.
(3) The operation of the input adjusting table is complicated.
(4) Determination of reverberation and other characteristics at the adjustment stage has to rely solely on the operator's acoustic impression and hence it is difficult to attain an objectively correct determination of these characteristics.
(5) Since the electric reverberation imparting device (i. e. , the echo machines 30 and 32) is employed, the sound field is liable to be affected by coloration.
It is, therefore, an object of the invention to provide a sound field control device and a method for controlling a sound field which have eliminated the above described disadvantages of the conventional sound field control device and are capable of readily creating a natural sound field simulating a real indoor concert hall in an outdoor space.